In the area of high output, so-called “thick film” heating elements are known, which have a very high degree of uniformity and an optimal surface/output ratio.
Such heating elements consist of enamels that are obtained from an enamel frit subjected to a curing temperature of the order of 850° C. Considering this production constraint, they are deposited on a metal substrate capable of withstanding such temperatures, e.g., of the steel, stainless steel or even alumina type. Such enamels, however, are not suitable for being deposited on an aluminium substrate.
Enamels exist that require curing temperatures lower than that indicated above and that are therefore capable of being deposited on an aluminium substrate. To do so, fluxing agents such as lead are added to the above-mentioned enamel frits. However, it is observed that the dielectric performance of heating elements obtained in this way is not at all satisfactory, as the fluxing agents render the enamel electrically conductive.